The present invention relates to the transparent GaAs photoelectric layer with a window made of a GaP single crystal substrate.
The transparent GaAs photoelectric layer which can be used for the image pick-up device is keenly desired.
The transparent GaAs photoelectric layer has a quantum efficiency higher than the conventionally used alkaline photoelectric layer over the wavelengths from the visible rays to the near infrared rays.
The transparent GaAs photoelectric layer when used in the image pick-up device has a sensitivity higher than the conventionally used alkaline photoelectric layer under the low illumination conditions, and this high sensitivity allows the transparent GaAs photoelectric layer to be used for the nocturnal shot camera.
The conventional transparent GaAs photoelectric layer will be described referring to FIG. 1.
FIG. 1 is an extended cross-sectional view of the conventional transparent GaAs photoelectric layer. The conventional transparent GaAs photoelectric layer has been fabricated in the following manner:
Buffer layer 2 consisting of an Al.sub.x Ga.sub.(1-x) As crystal is grown onto a GaP single crystal substrate 1 by means of liquid-phase crystal growth. GaAs electron emission layer 3 if formed on the Al.sub.x Ga.sub.(1-x) As buffer layer 2 by means of crystal growth.
Distortion caused by disorder in the crystal lattice between GaP single crystal substrate 1 and Al.sub.x Ga.sub.(1-x) As buffer layer 2 cannot be absorbed within Al.sub.x Ga.sub.(1-x) As buffer layer 2. This type of disorder causes GaAs electron emission layer 3 to be distorted. Thus, the transparent GaAs photoelectric layer with satisfactory surface structure and high quality cannot be obtained in the conventional transparent GaAs photoelectric layer, and it cannot be used for making the satisfactory image pick-up device.
The objective of the invention is to present a transparent GaAs photoelectric layer with satisfactory performance solving the problems.